A high-wear-resistant high-carbon high-manganese steel and its production method

Abstract

This invention discloses a high-wear-resistant, high-carbon, high-manganese steel and its production method. Its chemical composition and weight percentage content are: C: 0.92–1.05%, Si: 0.37–0.45%, Mn: 12.0–13.5%, P: ≤0.020%, S: ≤0.003%, Als: 0.03–0.05%, with the balance being Fe and unavoidable inclusions. The production process is as follows: KR hot metal desulfurization → converter smelting → argon blowing → LF refining → continuous casting into billets → hot rolling. This invention pioneers the use of a top-and-bottom blowing converter for smelting, followed by steelmaking in an LF ladle refining furnace, and continuous casting to produce wide-specification slabs with widths reaching 2.0–2.1 m. Its advantages include: the steel billets produced by continuous casting have a smooth surface, high dimensional accuracy, and require no surface finishing. It also simplifies the billet production process, improves metal yield, reduces the labor intensity of steelmaking workers, saves energy, and reduces consumption.

Description

Technical Field

[0001] This invention relates to the technical field of the metallurgical industry, specifically to a high wear-resistant high-carbon high-manganese steel and its production method. Background Technology

[0002] High wear-resistant high-carbon and high-manganese steel is mainly used in shot blasting machines. Due to its very high carbon and manganese content, continuous casting is very difficult to produce. The industry generally uses electric furnace steelmaking and die casting, which has many drawbacks, such as low production efficiency, long process, waste of manpower and resources, and low metal yield.

[0003] Currently, the main drawbacks of high-wear-resistant high-carbon high-manganese steel are its use in electric arc furnace steelmaking and ingot casting production, resulting in low production efficiency and high cost. While ordinary wear-resistant steel uses continuous casting, its composition incorporates elements such as C, Si, Mn, Nb, Ni, Cr, Mo, V, and B, leading to higher alloy costs. For example, Chinese patent applications with numbers CN88105287.6, CN201110136738.7, CN91108342.1, CN93117604.2, CN95103149.X, CN96118610.0, CN95103151.1, and CN96108157.0, among others, add one or more expensive alloys such as Mo, Nb, V, and Ni, further increasing costs. Therefore, developing a high-wear-resistant high-carbon high-manganese steel produced entirely by continuous casting is of great significance. Summary of the Invention

[0004] In view of the above problems, this invention proposes a high-wear-resistant, high-carbon, high-manganese steel and its production method to overcome or at least partially solve the above problems. This invention pioneers the use of a top-and-bottom blown converter for smelting, followed by steelmaking in an LF ladle refining furnace, and continuous casting to produce wide-specification slabs with widths reaching 2.0–2.1 m. Its advantages are: the steel slabs produced by continuous casting have a smooth surface, high dimensional accuracy, and require no surface finishing; simultaneously, it simplifies the steel slab production process, improves metal yield, reduces the labor intensity of steelmaking workers, and saves energy and reduces consumption.

[0005] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution:

[0006] A high-wear-resistant high-carbon high-manganese steel has the following chemical composition and weight percentage content: C: 0.92-1.05%, Si: 0.37-0.45%, Mn: 12.0-13.5%, P: ≤0.020%, S: ≤0.003%, Als: 0.03-0.05%, with the balance being Fe and unavoidable inclusions.

[0007] Preferably, its chemical composition and weight percentage content are as follows: C: 0.95-1.02%, Si: 0.38-0.43%, Mn: 12.5-13.3%, P: ≤0.015%, S: ≤0.002%, ALs: 0.035-0.045%, with the balance being Fe and unavoidable inclusions.

[0008] The method for producing the above-mentioned wide slab mainly includes the following steps:

[0009] The process flow is as follows: KR hot metal desulfurization → converter smelting → argon blowing → LF refining → continuous casting into billets → hot rolling.

[0010] 1) After KR desulfurization, the sulfur content in the molten iron is ≤0.001%;

[0011] 2) After smelting in a converter, the final temperature of the converter is controlled at 1610℃~1630℃, and the final oxygen content is 0.040~0.060%;

[0012] 3) The deoxidation process at the converter tapping stage is complete, with Al and ferrooxidation controlled to maintain an Alt content of 0.040%–0.070%. Alloying is also performed. Due to the very high carbon and manganese content in the molten steel, 9.0–10.0 kg / ts of recarburizing agent and 37.0–41.0 kg / ts of low-carbon metallic manganese balls are added at the converter tapping stage. The slag runoff at the converter tapping stage is ≤40 mm.

[0013] 4) Molten steel is bottom-blown with argon gas at the argon blowing station;

[0014] 5) The molten steel is refined by LF in five stages: carbon composition stage ~ temperature rise and deep desulfurization stage ~ manganese composition stage ~ fine adjustment of other alloys stage ~ temperature adjustment stage. Since the molten steel composition requires very high C and Mn content, very low temperature, and extremely low S content, the entire process completes these five stages in sequence. (1) Carbon composition stage: The first stage of carbon composition is chosen because the slag layer is relatively thin after arriving at the station (the slag layer gradually thickens as the LF treatment progresses), and the carbon feeding line can quickly enter the molten steel to achieve the purpose of precise control of carbon composition. The addition amount is 0.95~1.45kg / ts, and the feeding speed is 3~5m / s. (2) Temperature rise and deep desulfurization stage: The second stage is chosen because LF deep desulfurization requires high temperature, high basicity, and high reducing slag. If it is placed later, the temperature will drop rapidly with the addition of a large amount of alloys, which is not conducive to deep desulfurization. The LF arrival temperature is 1490~1500℃. The electrode heating begins, with a heating time of 15~25min and a heating rate of 4~5℃ / min. The temperature is raised to above 1560℃ (temperature before desulfurization). Lime and aluminum particles are added to form a reducing slag for desulfurization, and the S in the molten steel is controlled to be ≤0.002%. (3) Manganese composition stage: The temperature is raised to above 1600℃ (temperature before manganese addition), which is conducive to rapid deep desulfurization and can also compensate for the temperature loss caused by the subsequent addition of a large amount of low-carbon manganese metal balls. If the temperature is too low, the alloy melts slowly, and the alloy is not fully melted and is prone to agglomeration, which makes LF refining difficult. Moreover, the temperature drop in the molten steel process is very large, which makes it easy for the molten steel to not meet the thermodynamic conditions during the treatment process and not achieve the metallurgical effect of LF refining. The addition rate of LF refined low-carbon manganese metal balls is 93.0–107.0 kg / ts. Based on a 1°C temperature drop in molten steel for every 0.37 kg / ts of low-carbon manganese metal balls added, the temperature drop is 250–290°C. Due to the large addition rate, it should be done in small batches, multiple times, with each batch containing 7.0–8.0 kg / ts of low-carbon manganese metal balls to prevent incomplete alloy melting. (4) Fine-tuning other alloy stages: The Si content is controlled at the lower end of the range. Because in the LF deep desulfurization stage, as the reducibility of the slag increases, the Si in the slag will return to the molten steel, resulting in increased Si in the molten steel. The Al content is controlled at 0.030-0.060% during the LF refining process. Due to the large amount of low-carbon manganese metal balls added, the oxygen content is high, which will destroy the reducibility of the steel slag and increase the oxidizability of the steel slag, thereby causing the sulfur in the steel slag to return to the molten steel and causing the sulfur in the molten steel to exceed the standard. Therefore, the Al content is controlled during the LF process to ensure the reducibility of the steel slag. The Al content is controlled by feeding aluminum wire at the end of the LF refining process, and the Al content is controlled at 0.030-0.050%. In order to make the inclusions float fully, the bottom blowing argon time of the ladle is ≥10 minutes after the last batch of alloys is added. (5) Temperature adjustment stage: The temperature at the end of the LF refining process is controlled at 1450-1460℃. If the temperature is high, bottom blowing argon is used to stir and cool down. If the temperature is low, electrode heating is used to raise the temperature of the molten steel.

[0015] 6) This invention contains very high levels of C and Mn, and the casting temperature is extremely low (more than 100°C lower than that of conventional low-alloy steel). Continuous casting is extremely difficult and prone to leaks, so ingot casting is more commonly used in the industry. Continuously cast billets are prone to defects such as longitudinal cracks, edge cracks, and component segregation, easily leading to billet scrap. Traditional continuous casting methods cannot overcome this problem. The relevant parameters for steady-state casting in continuous casting are key in this invention, and the parameters of the mold flux are the challenge. During continuous casting, a mold flux with low basicity, low viscosity, and low melting point is selected. The basicity is 0.74-0.86, the viscosity is 0.07-0.13 Pa·s (at a temperature of 1300℃), and the melting point is 940-1000℃. The mold taper is set to 1.22-1.26%, and a medium-intensity cooling water flow rate is adopted for the mold. The wide-face cooling water flow rate is 4300-4400 L / min, and the narrow-face cooling water flow rate is 620-630 L / min.

[0016] 7) This invention contains very high levels of C and Mn. To avoid defects such as cracks and segregation in the billet during the casting process, the superheat is controlled at 20-30°C and the tundish temperature is controlled at 1430-1440°C.

[0017] 8) This invention contains very high levels of C and Mn. To avoid steel leakage during casting, a low billet pulling speed is controlled during continuous casting, with the pulling speed controlled at 0.7–0.9 m / min. During continuous casting, the fluctuation range of the molten steel level in the crystallizer is controlled within ±3 mm.

[0018] 9) Terminal casting: This invention contains very high C and Mn content, and the billet shrinkage is very large. It is very easy to leak steel at the end of the casting. Before the tundish is finished, the speed is reduced to 0.6 m / min to quickly clean the slag in the crystallizer. The time is less than or equal to 2 minutes. After the slag is cleaned, the stopper gas is turned off, the blind plate is plugged, and the casting speed is quickly increased to 0.9 m / min. Water is injected into the crystallizer through the water pipe to cool and solidify the upper surface of the crystallizer quickly. At the same time, the billet is quickly pulled out of the fan-shaped section of the continuous casting machine to complete the tail billet casting.

[0019] The various parameters for steady-state casting in continuous casting of this invention present a significant technical challenge. The molten steel contains very high levels of C and Mn, making the control of the basicity, viscosity, and melting point of the mold flux, as well as the matching of low superheat, low casting speed, and mold cooling rate crucial. Furthermore, this is combined with billet surface temperature control, where the billet surface temperature is segmented according to different casting flow lengths, as shown in Table 1 below.

[0020] Table 1

[0021]

[0022]

[0023] By adopting the above-mentioned control method, which differs from traditional casting, this technical problem can be overcome and the aforementioned defects in the cast billet can be avoided.

[0024] 10) The slab heating temperature is 1200~1240℃, the rough rolling temperature is 1000~1040℃, the finish rolling temperature is 780~820℃; the coiling temperature is 150~200℃.

[0025] The mechanisms of action of the various elements in this invention are as follows:

[0026] Carbon (C): To meet the mechanical properties of steel, especially to achieve high wear resistance, high hardness, and high toughness under high impact energy, the microstructure of the steel described in this invention requires a mono-austenitic structure. Carbon is beneficial for forming a mono-austenitic structure, and it also plays a role in solid solution strengthening, which helps to improve the wear resistance of steel. In particular, the higher the carbon content, reaching about 1%, the more significant the effect. However, too much carbon will reduce the plasticity and toughness of the steel, causing it to fracture. Therefore, the more suitable carbon addition is 0.92-1.05%, with a preferred C content of 0.95-1.02%.

[0027] Manganese (Mn): Manganese can combine with carbon to promote the formation of an austenitic structure in steel, ensuring its mechanical properties. With increasing manganese content, the strength, plasticity, and impact toughness of the steel all improve. Especially under higher impact conditions, it can achieve high wear resistance, high hardness, and high toughness. When the manganese content in the steel reaches approximately 13% and the carbon content reaches approximately 1%, and w(Mn) / w(C) = approximately 13, the strength, hardness, and toughness of the steel achieve the optimal balance. Therefore, the suitable amount of manganese added is 12.0–13.5%, with the preferred Mn content being 12.5–13.3%.

[0028] Silicon (Si): Silicon exists in austenite in solid solution form, playing a role in solid solution strengthening. Appropriate amounts of silicon can improve the solubility of carbon in austenite, thereby increasing the strength and hardness of steel and improving wear resistance. However, excessive silicon content can reduce plasticity. The suitable silicon addition is 0.37–0.45%, with an optimal Si content of 0.38–0.43%.

[0029] Aluminum (Al): Aluminum is a major deoxidizing element in steel, refining grains and fixing nitrogen in steel, thereby significantly improving its impact toughness. Aluminum can improve the wear resistance and oxidation resistance of steel; however, its disadvantage is that it affects the hot working and weldability of steel. The suitable Al addition amount in this invention is 0.03–0.05%, with a preferred Al addition amount of 0.035–0.045%.

[0030] Phosphorus (P): P easily leads to phosphorus dendrite segregation in cast billets, increases grain boundary brittleness, increases crack sensitivity, and causes internal cracks; phosphorus also deteriorates the toughness and plasticity of steel, and produces "cold brittleness" at low temperatures, which worsens weldability. Therefore, the phosphorus content in steel should be reduced as much as possible.

[0031] Sulfur (S) easily causes hot brittleness, reduces the ductility and toughness of steel, and reduces weldability; therefore, the sulfur content in steel should be reduced as much as possible.

[0032] The steel described in this invention contains a very high Mn content, resulting in a low initial hardness of only 200-250 HB. However, it exhibits strong work hardening ability, with hardness increasing and deformation rate accelerating during user use. Because the Mn content is as high as approximately 13%, a large number of Mn atoms replace iron atoms, significantly reducing stacking fault energy and thus facilitating deformation. This increases dislocation density, forming stacking faults and deformation substructures, exhibiting work hardening. Furthermore, the high C content allows supersaturated carbon to accumulate at dislocations, vacancies, and stacking faults during deformation. The interaction between sliding dislocations and dispersed carbide particles strengthens austenite. Therefore, although the initial hardness of the steel described in this invention is not high, its hardness and wear resistance increase with use.

[0033] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0034] This invention pioneered the use of a top-and-bottom blown converter for smelting, followed by steelmaking in an LF ladle refining furnace, and continuous casting to produce wide-specification slabs with widths reaching 2.0 to 2.1 meters. Its advantages are: the steel slabs produced by continuous casting have a smooth surface, high dimensional accuracy, and require no surface processing. At the same time, it simplifies the steel slab production process, improves metal yield, reduces the labor intensity of steelmaking workers, saves energy, and reduces consumption. Detailed Implementation

[0035] To enable those skilled in the art to better understand the technical solutions of the present invention, the preferred embodiments of the present invention are described below in conjunction with specific examples. However, these should not be construed as limiting the present invention and are merely examples.

[0036] Unless otherwise specified, the test methods or experimental methods described in the following examples are conventional methods; unless otherwise specified, the reagents and materials are obtained from conventional commercial sources or prepared by conventional methods.

[0037] The present invention will be further described in detail below with reference to specific embodiments.

[0038] The chemical components and weight percentages of Examples 1-10 and Comparative Examples 1-2 of the present invention are shown in Table 2.

[0039] The values ​​of the main steelmaking process parameters in Examples 1-10 and Comparative Examples 1-2 of the present invention are shown in Tables 3, 4 and 5.

[0040] The measured values ​​of the casting flow length and billet surface temperature during continuous casting in Examples 1-10 and Comparative Examples 1-2 of this invention are shown in Table 6.

[0041] The values ​​of the main hot rolling process parameters of Examples 1-10 and Comparative Examples 1-2 of the present invention are shown in Table 7.

[0042] Table 8 shows the main performance test statistics of Examples 1-10 and Comparative Examples 1-2 of the present invention.

[0043] The present invention discloses a method for producing high wear-resistant, high-carbon, and high-manganese steel, the process flow of which is: KR hot metal desulfurization → converter smelting → argon blowing → LF refining → continuous casting into billets → hot rolling.

[0044] Table 2. List of component values ​​(wt, %) for each embodiment and comparative example of the present invention

[0045] element 1 2 3 4 5 6 7 8 9 10 Comparative Example 1 Comparative Example 2 C 0.92 0.95 0.93 0.97 0.96 0.99 1 0.98 1.02 1.05 0.8 0.7 Si 0.37 0.38 0.4 0.39 0.42 0.41 0.43 0.42 0.44 0.45 0.2 0.3 Mn 12 12.5 12.3 12.8 12.7 13 13.2 12.6 13.3 13.5 5.6 8.1 ALs 0.03 0.032 0.035 0.039 0.04 0.036 0.042 0.038 0.045 0.05 0.01 0.02 P 0.015 0.013 0.012 0.016 0.011 0.014 0.01 0.018 0.009 0.011 0.025 0.028 S 0.0013 0.0012 0.0015 0.0011 0.0016 0.002 0.0023 0.0008 0.0018 0.0017 0.005 0.006

[0046] Table 3. List of main steelmaking process parameters for each embodiment and comparative example of the present invention.

[0047]

[0048] Table 4. List of main steelmaking process parameters for each embodiment and comparative example of the present invention.

[0049]

[0050] Continued from Table 4

[0051]

[0052]

[0053] Table 5. List of main steelmaking process parameters for each embodiment and comparative example of the present invention.

[0054]

[0055] Continued from Table 5

[0056]

[0057] Table 6. Measured values ​​of casting flow length and billet surface temperature during continuous casting in various embodiments and comparative examples of the present invention.

[0058]

[0059]

[0060] Table 7. List of main hot rolling process parameters (°C) for each embodiment and comparative example of the present invention.

[0061] Serial Number Heating temperature Roughing temperature Finishing temperature winding temperature 1 1216 1018 800 181 2 1210 1010 789 170 3 1213 1012 794 174 4 1218 1022 803 185 5 1240 1040 820 200 6 1227 1030 810 193 7 1224 1025 808 187 8 1222 1022 802 182 9 1236 1032 810 192 10 1205 1000 781 155 Comparative Example 1 1100 903 685 63 Comparative Example 2 1150 955 738 115

[0062] Table 8. Statistical table of main performance tests of various embodiments and comparative examples of the present invention.

[0063]

[0064]

[0065] As can be seen from Tables 2-8, the high wear-resistant high-carbon high-manganese steel obtained by the production method of the present invention has the following main properties: yield strength of 400-500MPa, tensile strength of 900-1000MPa, elongation A≥15%, and hardness of 200-250HB.

[0066] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be considered as limitations on the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for producing high-wear-resistant high-carbon high-manganese steel, characterized in that, The chemical composition and weight percentage of the high wear-resistant high-carbon high-manganese steel are as follows: C: 0.92-1.05%, Si: 0.37-0.45%, Mn: 12.0-13.5%, P: ≤0.020%, S: ≤0.003%, Als: 0.03-0.05%, with the balance being Fe and unavoidable inclusions; The production method includes the following steps: (1) KR hot metal desulfurization → (2) converter smelting → (3) argon blowing → (4) LF refining → (5) continuous casting into billets: the width of the billet is 2.0~2.1m → (6) hot rolling; In step (3), the molten steel is blown with argon gas through the bottom of the argon blowing station; In step (4), the molten steel undergoes LF refining, which is divided into five stages: Carbon composition stage: carbon wire addition is 0.95–1.45 kg / ts, and the wire feeding speed is 3–5 m / s; Deep desulfurization stage: the LF arrival temperature is 1490–1500℃, the treatment electrode heating begins, the heating time is 15–25 min, the heating rate is 4–5℃ / min, and the temperature rises to above 1560℃. Lime and aluminum granules are added to form a reducing slag for desulfurization, controlling the S content in the molten steel to ≤0.002%; Manganese composition stage: the temperature rises to above 1600℃, and the addition of low-carbon metallic manganese balls in the LF refining process is 93.0–107.0 kg / ts. ts, calculated based on a 1℃ temperature drop in molten steel for every 0.37kg / ts of low-carbon manganese metal balls added, the steel temperature drop is 250~290℃; Fine-tuning other alloy stages: Als is controlled at 0.030~0.060% during the LF refining process, and Als is controlled at 0.030~0.050% at the end of LF refining by feeding aluminum wire, and the bottom blowing argon time after the last batch of alloys is added is ≥10 minutes; Temperature adjustment stage: The temperature at the end of LF refining is controlled at 1450~1460℃. If the temperature is too high, bottom blowing argon is used to stir and cool down, and if the temperature is too low, electrode heating is used to raise the temperature of the molten steel; In step (5), a mold flux with low basicity, low viscosity, and low melting point is selected during continuous casting. The basicity is 0.74–0.86, the viscosity is 0.07–0.13 Pa·s / m³ at 1300℃, and the melting point is 940–1000℃. The mold taper is set to 1.22–1.26%. Medium-intensity cooling water is used, with a wide-face cooling water flow rate of 4300–4400 L / min and a narrow-face cooling water flow rate of 620–630 L / min. The superheat is controlled at 20–30℃. The ladle temperature is controlled at 1430-1440℃; the billet pulling speed is controlled at 0.7-0.9 m / min, and the fluctuation range of the molten steel level in the crystallizer is controlled within ±3 mm; during the final casting, the speed is reduced to 0.6 m / min before the tundish is finished to quickly remove the slag from the crystallizer, and the time is less than or equal to 2 minutes. After the slag is removed, the stopper gas is turned off, the blind plate is plugged, the pulling speed is quickly increased to 0.9 m / min, and water is injected into the crystallizer through a water pipe to quickly cool and solidify the upper surface of the crystallizer. At the same time, the billet is quickly pulled out of the fan-shaped section of the continuous casting machine to complete the tail billet casting. The surface temperature of the cast billet is controlled in segments according to different casting flow lengths, as shown in the table below: 。 2. The method for producing high-wear-resistant high-carbon high-manganese steel according to claim 1, characterized in that, Its chemical composition and weight percentage content are as follows: C: 0.95~1.02%, Si: 0.38~0.43%, Mn: 12.5~13.3%, P: ≤0.015%, S: ≤0.002%, ALs: 0.035~0.045%, with the balance being Fe and unavoidable inclusions.

3. The method for producing high-wear-resistant high-carbon high-manganese steel according to claim 1, characterized in that, Its yield strength is 400-500 MPa, tensile strength is 900-1000 MPa, elongation A≥15%, and hardness is 200-250 HB.

4. The method for producing high-wear-resistant high-carbon high-manganese steel according to claim 1, characterized in that, In step (2), the converter is used for smelting, and the final temperature of the converter is controlled at 1610-1630℃, with an oxygen content of 0.040-0.060%. The deoxidation of aluminum and iron is complete when the steel is tapped from the converter. The Alt content in the steel is controlled at 0.040% to 0.070%, and alloying is carried out. 9.0 to 10.0 kg / ts of carbon raiser and 37.0 to 41.0 kg / ts of low-carbon manganese metal balls are added when the steel is tapped from the converter. The slag discharge at the tapping point of the converter is ≤40 mm.

5. The method for producing high-wear-resistant high-carbon high-manganese steel according to claim 1, characterized in that, In step (6), the slab heating temperature is 1200~1240℃, the rough rolling temperature is 1000~1040℃, the finishing rolling temperature is 780~820℃, and the coiling temperature is 150~200℃.

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